text: from ..util import approx
  
  # noinspection PyUnresolvedReferences
  from ..util_mean import x, m_square, m_cube
  
  
  def test_scaled(x):
      # Test correctness.
      approx((2 * m_square)(x), 2 * m_square(x))
  
      # Test equality.
      assert 2 * m_square == m_square * 2
      assert 2 * m_square == m_square + m_square
      assert 2 * m_square != m_square * 3
      assert 2 * m_square != m_square + m_cube
  